WEDNESDAY, May 28, 2014 (HealthDay News) -- In the past three decades, the number of overweight and obese people worldwide has jumped from 857 million to 2.1 billion, a new analysis shows.

Not only that, the United States is home to the highest proportion of the world's obese people, at 13 percent.

The study shows that obesity is a major public health epidemic in both developing and developed nations, said the researchers at the Institute for Health Metrics and Evaluation (IHME) at the University of Washington in Seattle.

They analyzed data collected between 1980 and 2013 about children and adults in 188 countries.

Rates of overweight and obesity rose from 29 percent to 37 percent among men and from 30 percent to 38 percent among women. Rates of overweight and obesity among men were higher in developed nations, while rates among women were higher in developing nations.

The researchers also found that peak obesity rates are occurring at younger ages in developed nations, according to the study that appears May 29 in The Lancet.

Rates of overweight and obese children worldwide rose by nearly 50 percent between 1980 and 2013. In 2013, more than 22 percent of girls and nearly 24 percent of boys in developed nations were overweight or obese. The rates in developing nations were nearly 13 percent for both boys and girls.

"The rise in obesity among children is especially troubling in so many low- and middle-income countries," study author Marie Ng, an assistant professor of global health at IHME, said in an institute news release.

"We know that there are severe downstream health effects from childhood obesity, including cardiovascular disease, diabetes and many cancers. We need to be thinking now about how to turn this trend around," she said.

The study also found that more than 50 percent of the world's 671 million obese people live in 10 countries: the United States, China, Russia, Brazil, Mexico, Egypt, Germany, Pakistan and Indonesia.

"Obesity is an issue affecting people of all ages and incomes, everywhere," IHME Director Dr. Christopher Murray said in the news release. "In the last three decades, not one country has achieved success in reducing obesity rates, and we expect obesity to rise steadily as incomes rise in low- and middle-income countries in particular, unless urgent steps are taken to address this public health crisis."